Re: [PATCH 6/9] dma-buf: heaps: mtk_sec_heap: Add tee service call for buffer allocating/freeing

["Yong Wu (吴勇)" <Yong.Wu@mediatek.com>]

Hi Joakim,

Thanks very much for the reviewing.

On Wed, 2023-09-27 at 16:37 +0200, Joakim Bech wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  On Mon, Sep 11, 2023 at 10:30:35AM +0800, Yong Wu wrote:
> > Add TEE service call for secure memory allocating/freeing.
> > 
> > Signed-off-by: Anan Sun <anan.sun@mediatek.com>
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> >  drivers/dma-buf/heaps/mtk_secure_heap.c | 69
> ++++++++++++++++++++++++-
> >  1 file changed, 68 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/dma-buf/heaps/mtk_secure_heap.c b/drivers/dma-
> buf/heaps/mtk_secure_heap.c
> > index e3da33a3d083..14c2a16a7164 100644
> > --- a/drivers/dma-buf/heaps/mtk_secure_heap.c
> > +++ b/drivers/dma-buf/heaps/mtk_secure_heap.c
> > @@ -17,6 +17,9 @@
> >  
> >  #define MTK_TEE_PARAM_NUM4
> >  
> > +#define TZCMD_MEM_SECURECM_UNREF7
> > +#define TZCMD_MEM_SECURECM_ZALLOC15
> This is related to the discussion around UUID as well. These numbers
> here are specific to the MediaTek TA. If we could make things more
> generic, then these should probably be 0 and 1. 
> 
> I also find the naming a bit heavy, I think I'd suggest something
> like:
> # define TEE_CMD_SECURE_HEAP_ZALLOC ...
> and so on.

I will check internally and try to follow this. If we can not follow,
I'll give feedback here.

> 
> > +
> >  /*
> >   * MediaTek secure (chunk) memory type
> >   *
> > @@ -29,6 +32,8 @@ enum kree_mem_type {
> The "kree" here, is that meant to indicate kernel REE? If yes, then I
> guess that could be dropped since we know we're already in the kernel
> context, perhaps instead name it something with "secure_heap_type"?
> 
> >  struct mtk_secure_heap_buffer {
> >  struct dma_heap*heap;
> >  size_tsize;
> > +
> > +u32sec_handle;
> >  };
> >  
> >  struct mtk_secure_heap {
> > @@ -80,6 +85,63 @@ static int mtk_kree_secure_session_init(struct
> mtk_secure_heap *sec_heap)
> >  return ret;
> >  }
> >  
> > +static int
> > +mtk_sec_mem_tee_service_call(struct tee_context *tee_ctx, u32
> session,
> > +     unsigned int command, struct tee_param *params)
> > +{
> > +struct tee_ioctl_invoke_arg arg = {0};
> > +int ret;
> > +
> > +arg.num_params = MTK_TEE_PARAM_NUM;
> > +arg.session = session;
> > +arg.func = command;
> > +
> > +ret = tee_client_invoke_func(tee_ctx, &arg, params);
> > +if (ret < 0 || arg.ret) {
> > +pr_err("%s: cmd %d ret %d:%x.\n", __func__, command, ret,
> arg.ret);
> > +ret = -EOPNOTSUPP;
> > +}
> > +return ret;
> > +}
> Perhaps not relevant for this patch set, but since this function is
> just
> a pure TEE call, I'm inclined to suggest that this could even be
> moved
> out as a generic TEE function. I.e., something that could be used
> elsewhere in the Linux kernel.

Good Suggestion. I've seen many places call this, and they are
basically similar. Do you mean we create a simple wrap for this?
something like this:
int tee_client_invoke_func_wrap(struct tee_context *ctx,
                                u32 session,
                                u32 func_id,
                                unsigned int num_params,
                                struct tee_param *param,
                                int *invoke_arg_ret/* OUT */)

If this makes sense, it should be done in a separate patchset.

> 
> > +
> > +static int mtk_sec_mem_allocate(struct mtk_secure_heap *sec_heap,
> > +struct mtk_secure_heap_buffer *sec_buf)
> > +{
> > +struct tee_param params[MTK_TEE_PARAM_NUM] = {0};
> > +u32 mem_session = sec_heap->mem_session;
> How about name it tee_session? Alternative ta_session? I think that
> would better explain what it actually is.

Thanks for the renaming. Will change.

> 
> > +int ret;
> > +
> > +params[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
> > +params[0].u.value.a = SZ_4K;/* alignment */
> > +params[0].u.value.b = sec_heap->mem_type;/* memory type */
> > +params[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
> > +params[1].u.value.a = sec_buf->size;
> > +params[2].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT;
> > +
> > +/* Always request zeroed buffer */
> > +ret = mtk_sec_mem_tee_service_call(sec_heap->tee_ctx, mem_session,
> > +   TZCMD_MEM_SECURECM_ZALLOC, params);
> > +if (ret)
> > +return -ENOMEM;
> > +
> > +sec_buf->sec_handle = params[2].u.value.a;
> > +return 0;
> > +}
> > +
> > +static void mtk_sec_mem_release(struct mtk_secure_heap *sec_heap,
> > +struct mtk_secure_heap_buffer *sec_buf)
> > +{
> > +struct tee_param params[MTK_TEE_PARAM_NUM] = {0};
> > +u32 mem_session = sec_heap->mem_session;
> > +
> > +params[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT;
> > +params[0].u.value.a = sec_buf->sec_handle;
> > +params[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
> Perhaps worth having a comment for params[1] explain why we need the
> VALUE_OUTPUT here?

Will do.

> 
> -- 
> // Regards
> Joakim
> 
> > +
> > +mtk_sec_mem_tee_service_call(sec_heap->tee_ctx, mem_session,
> > +     TZCMD_MEM_SECURECM_UNREF, params);
> > +}
> > +
> >  static struct dma_buf *
> >  mtk_sec_heap_allocate(struct dma_heap *heap, size_t size,
> >        unsigned long fd_flags, unsigned long heap_flags)
> > @@ -107,6 +169,9 @@ mtk_sec_heap_allocate(struct dma_heap *heap,
> size_t size,
> >  sec_buf->size = size;
> >  sec_buf->heap = heap;
> >  
> > +ret = mtk_sec_mem_allocate(sec_heap, sec_buf);
> > +if (ret)
> > +goto err_free_buf;
> >  exp_info.exp_name = dma_heap_get_name(heap);
> >  exp_info.size = sec_buf->size;
> >  exp_info.flags = fd_flags;
> > @@ -115,11 +180,13 @@ mtk_sec_heap_allocate(struct dma_heap *heap,
> size_t size,
> >  dmabuf = dma_buf_export(&exp_info);
> >  if (IS_ERR(dmabuf)) {
> >  ret = PTR_ERR(dmabuf);
> > -goto err_free_buf;
> > +goto err_free_sec_mem;
> >  }
> >  
> >  return dmabuf;
> >  
> > +err_free_sec_mem:
> > +mtk_sec_mem_release(sec_heap, sec_buf);
> >  err_free_buf:
> >  kfree(sec_buf);
> >  return ERR_PTR(ret);
> > -- 
> > 2.25.1
> >